Hi , was just wondering If it was possible to move the AFM to another position in the intake, after the Inter cooler. or will it not work with being blown on instead of sucking, I have an unichip so could I get a remap to compensate??? thanks. G

it will need to remain on the atmospheric (pre turbo) side mate.
you can move it but make sure all hoses to and from are of equal diameter and have no step up's or reducers, just my 2p

DAMN ! ah well cheers mate , as for the reducers/steppers I do use thoes to fit my SIP its unavoidable.

The afm is part of the fuel calculation at the ecu i believe, so moving it further away from the air intake would cause it to react slower to changes maybe?

Ross

Ross was hoping that the mapping would correct it.

It would on boost. The ecu still controls it off boost, so would be a tad lumpy on/off throttle.

Ross

I dont think I have heard of people with SIP's complaing of rough idle's ???

EDIT. the lambda sensor would control the idle as well.

fair enough, i suppose with a reducer, the air flow volume is the same, it's just flowing at a faster rate at that given point

Just a theory here, but surely moving it to after the intercooler, it will still measure the same amount of air, as it would before the intercooler. None of the intake air is bled off at any point is it? Except maybe for the ICV? No idea how it would cope with being pressurised either, probably leak air everywhere.

I dont think it would like having hot air passed over it either(no idea what charge temps normally are?). Just wondering why you would want to move it?

Cheers

Ben

SIP is the one of the causes for concern with idling woes.

Ross

Actually ignore the hot air being passed over it, just realised they are hot wire devices on 20VT, so heat the air up any way.

Anyone anygood with physics? As Karlothen says, if you are using a reducer, then are you increasing the gas speed over the element? Therefore cooling it faster, inturn making the ECU believe there is more air than there is, making the whole thing run rich?

Ben

Ignore all that, as the air flow meter doesnt change size. I am, as usual, talking crap.

the only reason i'm not to sure about moving the unit "post turbo" is because i have no idea what the max air flow rate the meter can read, obviously the unit is built to meet certain limits within it's day to day life,
i'm really not to sure if it could cope on a day to day basis with sampling upto xxx times the standard flow rate?
add in the fact that you will eventualy get some oil blow by from the turbo seals and the fact that the crank case breather will be venting oil vapour pre turbo..... i'm pretty sure the meter will get messy pretty quickly.
ok you can remove the crank case breather, but i'm still not sure about having a sensitive meter post turbo.

just my 2p

karl

Ben I think your thinking what I thought , that the AFM measures air flow not temp, I was just wondering though with a remap it would compensate the change....

Karl , the air flow would be the same before and after the turbo, just one is sucking and the other is blowing??

Yeah one side is pressurized the other isnt as much so.

Ross

Good point there Karl.

Out of interest, does anyone have a diagram of the Coupe inlet system, all the pipes etc. There seems to be hundreds all over the place and its always nice to know what does what.

its not pressure its airflow

Ahhhhh, but surely, if you have for example, 1.2 bar boost on one side, there must be 1.2 bar of vacuum on the other side?

Ben (Where are all the physicists when you need em?)

Not quite I think, there would be more pressure pushing the air into the engine, than sucking it through the filter

ahhh, good point
i'll use the girl friend nagging me to get off the computer for my lapse in concentration

Is does get confusing, but this cheap larger I am drinking is helping

But surely airflow must be related to pressure some how?

i can see where your coming from, but there would be an equal rate and volume of air "pre turbo" and if the air post turbo is being displaced at xxx then the area pre turbo must be replaced at an equal rate......don't you just love gravity

When I wake up in the morning, this will all be solved and will be in simple english I understand!

Ben

Right I've just got my old A Level physics book out. I'm going to where I find my best ideas (the toilet) and will return with some important formulae!

yes, increase the pressure and the flow rate will be faster

yeah i knew i could make 100 posts, if i talked about some thing i don't know LOL

but the quantity the same??

I just got over the 1000 with this

Yeah i see what ya mean about pressure genic. Im still thinking reaction time would be down. Regardless of mapping, the ecu would still take longer to detect a change in air flow.

Ross

As the boost pressure is increasing, the air flow will be faster going into the turbo than by the time it reaches the engine. Thats what causes the pressure to rise. Then when the dump valve opens it levels it all out again. Also, IIRC the AFM shouldnt be too close to the turbo, but I've forgotten why